A conventional waterproof relay connector 1 for solar cell-use in described, for example in Japanese Unexamined Patent Application No. 2001-257027 filed Mar. 10, 2000, and Japanese Unexamined Patent Application No. 2002-009326, filed Jul. 26, 2000, each of which is hereby incorporated by reference herein in its entirety. A conventional waterproof relay connector of this type includes a plug 2 and a socket 3, with respective power line cables 4 were connected thereto, as illustrated in FIGS. 3 and 4. The plug 2 has a plug pin 6 provided in a protruding state inside a cylindrically-shaped plug housing 5, and is connected to the cable 4 power line. Additionally on a sidewall of the plug housing 5, are provided engaging parts 7 that are penetrated at mutually symmetric location in the axial direction.
The socket 3 is provided with a socket housing 8, equipped internally with a contact for connecting, into which the plug pin 6 in the plug 2 is inserted, and the contact connects to the cable 4 on the socket 3 side. Formed integrally on the sidewall of the socket housing 8 are latching protrusions 9, arranged at symmetrical locations, and projecting along the sidewall and toward the tip thereof. The latching protrusions 9 are inserted into the engaging parts 7, and latching parts 9a at the tip portions of latching protrusions 9 engage the edges of openings in the engaging parts 7, and latch so as not to be easily pulled out. Moreover, attached to the base of the socket housing 8 is a sealing member 10, such as an O-ring, that mates water-tightly with the plug housing so as to create a waterproof state in the interior where the contact is located.
In the case of the abovementioned prior art, even when the plug 2 and the socket 3 are engaged in a mated state for example as shown in FIG. 4, the engagement may dislodge due to the application of some external force against the latching parts 9a at the tip portions of latching protrusions 9 of the socket housing 8. For example, the engagement may dislodge easily as a result of holding and pinching the latching parts 9a in one's hand, causing the cable 4 connections to become dislodged inadvertently.